Plug back tool for cementing wells



Dec. 15, 1936. Q BATES 2,064,336

PLUG BACK TOOL FOR CEMENTING WELLS Filed se t. 20, 1955 2 Sheets-Sheet 1 Dec. 15, 1936. s. Q. BATES 2,064,336

PLUG BACK TOOL FOR CEMENTING WELLS Filed Sept. 20, 1935 2 sheets-sheet 2 5Q Backs 3 MSW Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE PLUG BACK TOOL FORCEMENTING WELLS My invention relates to the placing in deep wells of a plug of cement for the purpose of shutting off the entrance of fluid to the hole at the point where the plug is placed.

The usual practice in plugging back wells, or cementing off the lower water-producing sands, consists of pumping a charge of fluid cement down the drill stem or tubing, the landing spot being determined by the amount of water pumped down on top of the cement. The very nature of this operation precludes its use in plugging back a short hole requiring the accurate placement of v a small amount of cement without endangering the producing sand. It is also impractical to accurately land the cement at the right spot.

The plug back device here shown has for its object to overcome the above objections and to provide a new and greatly improved method of plugging off a small lower section of sand. It is desired to provide positive placement of a small amount of cement in position where it does not come in contact with the oil producing sand.

It is a further object to accomplish the location of the cement by actual measurement, which eliminates estimating the amount of fluid to pump down and it also eliminates the job of actually pumping a definite amount of'fluid in order to land the cement at its proper place.

Another very important object is to improve over present methods in the elimination of the time required for the setting of cement slurry about seventy-two hours. With my device the operation may use quick-setting cement, requiring anywhere from fifteen to thirty minutes to 5 set, thus accomplishing a great saving for the operation.

Another object is to provide a structure whereby the operator can actually measure the height of the cement plug and determine whether it is 4 accurately placed.

Another object is to provide a device whereby the charge-of cement may be packed down and pressed solidly into the bottom of the hole by mechanical means.

It is a further object of the invention to provide a device whereby the cement charge may be .formed in a package or container which allows the charge to be handled as a unit and moved positively into the position where it is to set.

In the drawings herewith, Fig. 1 is a central longitudinal section through the lower end of my device shown in position adjacent the lower end of the well.

55 Fig. 2 is a similar view showing the upper portion of the plug setting device, Fig. 2 being a continuation of the upper end of Fig. 1.

Fig. 3 is a side elevation of my device showing the same removed from the well.

Fig. 4 is a central longitudinal section similar- 5 to Fig. 1 but disclosing a slightly different embodiment of the invention.

Fig. 5 is a transverse section on the plane 55 of Fig. 2.

Figs. 6 and '7 are transverse sections on the 1 planes 5-6 and 1-1 of Fig. 1.

Fig. 8 is a similar transverse section on the plane 88 of Fig.4. 7

In the drawings herewith I have illustrated my device as placing a charge of cement in the lower 15 end of the well bore I, it being the purpose of the invention to place a charge of cement at the lower end of the well to cut off the entrance of fluid below and around the plug to the well.

My device includes a tubing string 2, which is 20 of uniform diameter to a point within the device which I employ. At the point shown at 3 in Fig.

2 the diameter of the tubing 2 is slightly reduced; the lower reduced portion 4 being connected to the section 2 by a collar 3. This collar has 25 lateral, downwardly discharging, fluid openings 5 therein.

Slidable on the tubing 2 is a special nipple 6, said nipple being tapered downwardly at 'l to provide flattened areas shown at 8 in Fig. 5, 30 upon which casing engaging slips 9 may seat. The nipple 6 connects at its lower end with a section of pipe III which forms a housing for the cement-discharging apparatus, aswill be later described. l

The inner portion of the nipple 6 is adapted to fit about the tubing 2. There is an enlarged recess at H to receive packing to seal about the tubing 2 and a gland l2 above the packing serves to compress the same in the box. The upper end 40 of the nipple is further enlarged to provide a threaded chamber I3 to receive a tubular nut l4 which serves to compress the gland l2 against the packing. The outer pipe or housing I!) is connect 3d at its lower end by means of a coupling I5 to a swaged housing IS, the said housing being of larger diameter than the housing Ill.

Within the housing section 16 is a cement bucket i1 within which a sack, of fabric, paper, or other flexible material, containing the cement I8 may be placed. The upper end of the cement bucket is swaged inwardly to provide a neck at I 9 which engages closely about the lower end 20 of the tubing. I A seal is provided between the upper neck of the bucket and the tubing which I includes a stumng box 2| with packing 22 therein compressed in position by a gland 23 and a tubular nut 24.

The cement bucket is spaced from the housing [8 by spacing lugs 25 at its upper end and its lower end is provided with laterally extending lugs 28 contacting with the inner wall of the housing. At the lower end of the said housing IS the cement bucket is closed by a cap 21, which is preferably made up of a plug of cement of somewhat larger diameter than the interior of the cement bucket and held in position closing the lower end of the bucket by a hemispherical shaped gasket 28 of sheet metal, such as copper or other soft material, the upper ends of which are clamped within a groove 29 at the lower end of the bucket by means of a ring 30' formed at the upper end of the shoe 3|, screwed within the lower end of the housing. It will be noted that when the shoe 3| is screwed upwardly in the" bucket .whilethe device is going into the well. i

The lower end of the tubing 20 within the cement bucketis belled outwardly at 33 and is I fastened to a piston 34 resting upon the upper end ,of the charge of cement l8. This piston forms a sealing fit. within the cement bucket and .when pushed downwardly by means of the tubing the cement charge will be forced against the plug 21 in such manner as to shear the holding gasket 28 from its position clamped into the lower end of the bucket and allow the plug 21 to be forced downwardly and to thus discharge the cement into the bottom of the hole.

To. anchor the housing and bucket in position in the well the upper end of the section III referred to has slidable thereon a ring 35. Said ring has a bayonet slot 36 therein to receive a radially projecting pin 31 on the housing I 0. There are arms 38 fixed to the ring and bowed outwardly to engage against the interior of the 'casing 38. At the upper end of the spring arms;

38 is a second ring 48, which is also slidable on the cylindrical outer surface of the housing I8.

The slips 9 previously referred to are mounted onthe upper ends of arms 4| of steel, said arms .being secured at their lower ends to the ring 35 so that the said slips are spaced uniformly above' the'said ring, and are in registration with the flattened areas 8 of the nipple 6.

When this device is in use it is assembled together in therelation shown. in Figs. 1, 2 and 3,

the cement l8 enclosed within a sack or container' -'done by raising the device the proper distance of! the bottom of the well and rotating slightly so as to bring the pin 3'! into the vertical portion of the bayonet slot l8, after which the lowering of'the device will move the housing downwardly away from the ring "and bring the dogs 9 into 'locking engagement between the nipple 3 and the casing-38. It will then be possible. to move the tubing 2 downwardly relative to the housing and cement bucket and force the piston 34 against the cement and, by breaking of! the cap 28, dis charge the cement downwardly into the bottom of the well. The said charge of cement may be then tamped tightly into position at the bottom of the hole so that it will completely fill and close of! the same. The water in the hole mixing with the cement thus discharged will quickly set and serve to plug off the well bottom.

It will be obvious that the exact height of the upper end of the plug relative to the surface may be readily measured through the length of tubing 2 extending upwardly from the cement to the surface. The tubing may rest upon the cement so as to exactly note the position thereof and will serve to inform the operator as to the exact position of the plug.

' In Figs. 4 and 8 I have shown a slightly different modification of the invention in which the lower housing and cement bucket are altered. In this form the upper end and the anchoring means may be understood as being the same as is shown in Fig. 2, with the exception that the coupling 3' does not have fluid discharging openings therein. ,The length of the tubing 4' below the coupling passes downwardly through the charge of cement l8 and is flxed at its lower end by being screwed at 42 into a cap 43 of frangible material such as cast iron or the like. Said cap 43 is screwed at 44 into the lower end of the cement bucket 45. It is to be noted in this case that the housing about the cement bucket is entirely eliminated, the cement bucket being attached directly to the lower end of the housing member III by means of a coupling IS. The piston 46 is annular in shape and is secured upon the tubing 4 which extends downwardly therethrough as previously noted. The tubing 4' has also secured thereto by welding or other means a sleeve 41 having radially extending vanes or arms 48 which may be used as stirrers or agitators in handling the cement.

In this form of the invention the water employed in washing the hole is forced downwardly through the tubing 4' directly into the well bottom so that it may be washed free of foreign material. The device is then anchored in position and the tubing 4' is forced downwardly so as to fracture the lower cap 43 and permit the discharge of the .cement into the bottom of the hole. The agitating members 48 upon the tubing may be used to stir up the cement and assure that it is evenly distributed so as to flll the entire bottom of the hole. While this form of the invention is simpler,

the device shown in Figs& 1 to 3, inclusive, is preferred under ordinary circumstances because of its somewhat more positive operation. The ad- ;yantages of this device lie in the fact that the charge of cement maybe of the quick-setting type and may be kept entirely dry and sealed ofi from the liquid until the moment when it is to be discharged into the bottom of the well. It may then be mixed with the water and tamped in position and will set rapidly so that the plug of cement is in flxed and rigid position before the device itseli.- is removed from thehole. I am thus enabled to place the charge of cement in position at the bottom of the hole and plug off the same quickly and accurately. The further advantages will be obvious to those skilled in the art.

What is claimed as new is:

1. A device for setting cement well plugs inpipe extending through said bucket and closure, a piston on said pipe above the cement in said bucket to force out cement, means to anchor said bucket at the desired point in the well, and means including said piston to force said'closure and said cement from said bucket.

2. A device for setting cement well plugs including a cement bucket, releasable closure means to seal the lower end thereof, a piston above the cement in said bucket, means to anchor said bucket at the desired point in the well, means to discharge fiuid past said cement into the well bore to wash the same, and means including said piston and said discharge means to force said closure and said cement from said bucket.

3. A device for plugging Wells with cement including a tubing, a cement bucket, a reduced neck on said bucket having a slidable connection with said tubing, a plug releasably closing the lower end of said bucket, means to seal the upper end of said bucket, means to wash the well below said bucket, and means to anchor said bucket in the well, said. tubing being then movable downwardly against said sealing means to force said cement and said plug from said bucket.

4. A device for plugging wells with cement including a tubing, a cement bucket, a slidable connection between said bucket and said tubing, sealing means in said connection, a plug releasably closing the lower end of said bucket, means to seal the upper end of said bucket, means to wash the well below said bucket, means to anchor said bucket in the well, said tubing being then movable downwardly with said sealing means to force said cement and said plug from said bucket.

5. A closed container for dry cement, means to introduce said container into a well, means including said introducing means towash the well, and means to seal the upper end of said container and movable longitudinally of said container to open said container and discharge said cement into the well.

6. A closed cement container, means including a tubing to introduce said container into a well, means to anchor said container at the desired level in the well and means operated by said tubing to open said container and force said cement from said container into said well.

7.- A cement bucket, a tubing slidably connected with said bucket, means to seal the lower end of said bucket, means operated by said tubing to support said bucket in said well, said tubing being then slidable downwardly to break said seal and discharge said cement into said well.

8. A cement bucket, a tubing slidably connected with said bucket, a frangible seal for the lower end of said bucket, a piston above the cement in said bucket, means operable through said tubing to support said bucket at the desired levelin said well, means on said tubing engaging said piston to force said cement and said frangible seal from said bucket.

9. A cement bucket, a tubing slidablyconnected with said bucket, a frangible seal for the lower end of said bucket, a piston above the cement in said bucket, means operable through said tubing to support said bucket at the desired level in said well, means on said tubing engaging said piston to force said cement and said frangible seal from said bucket, and means to stir said cement and distribute the same in the well hole.

SIDNEY Q. BATES. 

